title: PKA controls calcium influx into motor neurons during a rhythmic behavior.
abstract: Cyclic adenosine monophosphate (cAMP) has been implicated in the execution of diverse rhythmic behaviors, but how cAMP functions in neurons to generate behavioral outputs remains unclear. During the defecation motor program in C. elegans, a peptide released from the pacemaker (the intestine) rhythmically excites the GABAergic neurons that control enteric muscle contractions by activating a G protein-coupled receptor (GPCR) signaling pathway that is dependent on cAMP. Here, we show that the C. elegans PKA catalytic subunit, KIN-1, is the sole cAMP target in this pathway and that PKA is essential for enteric muscle contractions. Genetic analysis using cell-specific expression of dominant negative or constitutively active PKA transgenes reveals that knockdown of PKA activity in the GABAergic neurons blocks enteric muscle contractions, whereas constitutive PKA activation restores enteric muscle contractions to mutants defective in the peptidergic signaling pathway. Using real-time, in vivo calcium imaging, we find that PKA activity in the GABAergic neurons is essential for the generation of synaptic calcium transients that drive GABA release. In addition, constitutively active PKA increases the duration of calcium transients and causes ectopic calcium transients that can trigger out-of-phase enteric muscle contractions. Finally, we show that the voltage-gated calcium channels UNC-2 and EGL-19, but not CCA-1 function downstream of PKA to promote enteric muscle contractions and rhythmic calcium influx in the GABAergic neurons. Thus, our results suggest that PKA activates neurons during a rhythmic behavior by promoting presynaptic calcium influx through specific voltage-gated calcium channels.
authors.affiliation: Graduate Program in Genetic, Molecular and Cellular Biology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America ; Zilkha Neurogenetic Institute, Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Han
authors.initials: H
authors.lastname: Wang
authors.forename: Derek
authors.initials: D
authors.lastname: Sieburth
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000235:genetics* / Q000502:physiology; D020134:Catalytic Domain / Q000235:genetics; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics* / Q000378:metabolism; D003672:Defecation / Q000235:genetics / Q000502:physiology; D059330:GABAergic Neurons / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009046:Motor Neurons / Q000378:metabolism*; D009119:Muscle Contraction / Q000235:genetics* / Q000502:physiology; D009124:Muscle Proteins / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D015220:Calcium Channels; C109164:Egl-19 protein, C elegans; D008565:Membrane Proteins; D009124:Muscle Proteins; C093204:unc-2 protein, C elegans; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium